A seat device is provided with: a first air bag expanding and contracting inside a seat surface skin； a holding member for holding the first air bag and movable along the inner surface of the seat surface skin； a drive device for moving the holding member so as to change the arrangement of the first airbag； and a second air bag independent of the first air bag, the second air bag expanding inside the seat surface skin so as to press the seat surface skin to separate the seat surface skin from the first air bag.
